Any issues with appearance of Polished carbon X-squared frames..

So I've been thinking of adding the Polished Carbon frame to by X-metal pairs and heard there are some issue with the consistency of the color/finish across the frame.
I have a friend in the UK who has had multiple pairs but could only find a couple of pairs that looked consistent across the frame
I never heard or knew about this.
Any pointers (sorry no pics to offer to show off the flaws)?
Thanks in advance Folks!!